This invention is in the field of prostheses and is more particularly directed to a metacarpophalangeal prosthesis for replacement of the natural metacarpophalangeal joint.
Prior known prostheses for joint replacement have been provided in a variety of forms employing metal, plastic, silicone rubber and other components as evidenced by U.S. Pat. Nos. 3,462,765; 3,488,779; 3,506,982; 3,593,342; 3,760,427; 3,795,922; 3,805,302; 3,868,730; 3,893,196; 3,899,796; 3,906,550; 3,946,445; 3,978,528; 3,986,212; 3,990,116; 3,991,425; 4,011,603; 4,059,854; 4,065,817; 4,131,957; 4,146,936; 4,158,893 and 4,172,296.
While the prior known protheses have been beneficial in many ways, none have been able to duplicate the action of the natural metacarpophalangeal joint. Specifically, the natural joint does not merely provide a pivotal hinge function without any lateral motion but instead permits lateral motion when the joint is extended in linear manner but does not permit such motion when the joint is in a bent or flexed position such as when the distal and proximal components are in a generally perpendicular relationship. Consequently, duplication of the natural joint motion would require that any prosthesis allow for a full range of motion when the joint is in its extended linear condition while not allowing lateral motion when the joint is in its flexed or bent condition. No prior known prosthesis has been able to accomplish this result.
Therefore, it is the primary object of this invention to provide a new and improved prosthesis.
A more specific object of the present invention is the provision of a new and improved metacarpophalangeal prosthesis.